Physics 2 Final Exam

magnet

an object that produces a magnetic field which in turn exerts a magnetic force on objects within the field

do magnets occur naturally or artificially?

both

why cant the north and south poles of a magnet be separated

because if you break a magnet in half, it will form new poles along the break point

are magnets monopoles or dipoles

dipoles

ferromagnets

strong magnets made of iron, nickel or cobalt that are strongly attracted to magnetic fields, and are magnetized by being exposed to a magnet

What can make ferromagnets permanent magnets?

heating and then cooling or tapping the material

Curie temperature

the temperature needed to turn a Ferromagnets material into a magnet

Electromagnet

magnet produced by electric current; only produce a magnetic field while the current is flowing

magnetic field lines

-direction of field is tangent to field lines

-strength of field is proportional to the closeness of the lines

-field lines never cross

-continuous and form loops between the north and south poles of a magnet

Magnetic fields often cause particles to____. What is the force on the particles?

curve; the magnetic force is equal to the centripetal force

Hall Effect

occurs when a magnetic field is applied perpendicular to the current flow in a conductor, resulting in a voltage difference across the conductor.

magnetic force moving through wire formula

F=ilBsin theta

concentric loops

the magnetic field around long wires that carry current like overhead powerlines

right hand rule modified for concentric loops

thumb represents current flow, fingers curl in the direction of magnetic field

if two currents are traveling in the same direction, the force between them will be

attractive

if two currents are traveling in opposite directions, the force between them will be

replulsive

if the loop of wire of motors is connected to a shaft, what will the electric energy be converted to due to the rotation?

mechanical energy

which equation shows all the direct proportionality of torque?

T= NIABsin theta

Ampere’s Law

states that the magnetic field in space around an electric current is proportional to the electric current which produces it.

solenoid

long coil of a current carrying wire attached to a battery, produces a strong and uniform magnetic field inside the coil, the tighter the coil, the greater the magnetic field B

Induction

the process of generating emfs and currents through magnetic fields

magnetic flux

emf produced by change in direction of magnetic field

Lenz’s Law

a principle stating that the direction of induced current is such that it opposes the change in magnetic flux that produced it.

if the magnetic flux is increasing, then induced current is in

the opposite direction as the external field

if the magnetic flux is decreasing, then induced current is in

the same direction as the external field

if the magnetic flux is not changing, then induced current is

0

back emf/counter emf

the voltage generated when a motor turns and produces mechanical energy, so magnetic flux is created which creates and emf

Eddy current

reverse current flow caused by back emfs

what are generators used to produce?

alternating current (AC)

how are generators the opposite of motors?

they convert mechanical energy into electric energy

What does a generator consist of?

Many loops of wire wound on an armature that can rotate in a magnetic field; the axle is turned by mechanical means 

transformer

a device for increasing or decreasing an alternate current voltage

what does a transformer consist of?

a primary and secondary coil that can be interwoven or linked by an iron core

step up transformer

if the secondary coil has more loops than the primary coil

step down transformer

if the primary coil has more loops than a secondary coil

inductance

a measure of how effectively a device can induce an EMF by changing magnetic flux

two basic types of inductance

mutual inductance: one device upon another

self-inductance: a device upon itself

reactance

the opposition to the flow of alternating current in a circuit due to capacitance or inductance.

inductive reactance

the opposition to the flow of alternating current caused by inductance in a circuit.

capacitive reactance

the opposition to the flow of alternating current caused by capacitance in a circuit.

What is a wavicle?

A term used to describe light as a wave and a particle

What does light need to interact with in order to be seen?

A surface

When light encounters a boundary it can either….

reflect (bounce back) or refract (bend)

Incident angle

the angle creates when a light ray encounters a smooth boundary, it bounces back at the same angle it had; Theta i = Theta r

spectacular reflection

reflection of light that creates the incident angle and reflected angle

diffuse refelction

a variety of scattered angles occuring when a light ray encounters a rough boundary

when light changes from one material to another, its speed changes based on the

density of the material

fastest light can travel

c= 3.0 × 10⁸ m/s

index of refraction, n

comparison of the fastest speed to the speed in a material

the higher the index of refraction, the _______ the speed of light in the material

slower

if 1st material index of refraction (n) low, then light bend

toward normal

if 1st material index of refraction (n) high, then light bend

away from normal

Snell’s Law

describes the relationship between the angles of incidence and refraction when light passes between two media with different indices of refraction. It is mathematically expressed as n1 sin(θ1) = n2 sin(θ2), where n is the index of refraction and θ is the angle.

total internal reflection

when light bends so much it bounces back into the original material

when does total internal reflection happen?

only when light goes from a high index material to a low index material

What must be true about the angle for total internal reflection to occur?

The incoming angle must be greater than the critical angle.

What is the refracted angle at the critical angle?

It becomes 90° (the light travels along the boundary).

What creates mirages?

Total internal reflection caused by layers of air with different temperatures.

what is a lens?

any transparent material that causes light to refract and come into focus

reflection vs. refraction

Reflection is the bouncing back of light when it hits a surface, while refraction is the bending of light as it passes through different mediums.

All lenses have a focal point? what is a focal point?

distance from the lens where objects far from the lens will come into focus

what are the two ways magnification can be found

it can be found using the heights of the image and object, and it can be found using the distances of the image and object from the lens

optical power

the reciprocal of the focal length

Real type of image

when two light rays actually meet

virtual type of image

when two light rays only seem to meet

upright orientation of image

has the same orientation as the original object

inverted orientation of image

has the opposite orientation as the original object

what types of images are defined by magnification?

reduced, same, or enlarged

two basic types of lenses

converging and diverging

converging lens (football shaped) properties

• have POSITIVE focal lengths

• form both real and virtual images

• form both upright and inverted images

• can magnify or reduce

diverging lens shapes are called

concave lenses

diverging lens(hourglass shaped) properties

• have NEGATIVE focal points

• produce virtual, upright, and reduced images only

how do curved mirrors alter the law of reflection

causes images to be real or virtual and enlarged or reduced

how is a converging mirror different to converging lens?

it is concave in shape (opposite of lenses)

how is a diverging mirror different from a diverging lens?

it is convex in shape (opposite of lenses)

optical system

combines two or more lenses or combinations of lenses and mirrors

lens closest to the eye

eyepiece

the other lens or mirror is called the

objective

what does a compound microscope use and produce

uses two converging lenses and produces a real inverted image

angular magnification of a telescope

ratio of the focal lengths of the objective and the eyepiece

two basic types of telescopes

refracting and reflecting

refracting telescope

two lenses are used with the objective lens forming a real image inside the focal length of the eyepiece lens

reflecting telescope

objective is a concave mirror instead of a convex lens

what is dispersion?

splitting light into different colors because each color bends differently

what is interference?

when waves overlap and make bright stops (constructive) or dark spots (destructive)

what is diffraction?

light bending or spreading out when it goes through a small opening or goes around an edge

what is polarization?

making light vibrate in only one direction

How does increasing the number of slits in a diffraction grating change the diffraction pattern?

Increasing the number of slits in a diffraction grating leads to a brighter and more defined diffraction pattern, enhancing the separation between the bright spots.

What causes polarization?

Polarization is caused by the absorbing or reflecting of light waves, which restricts their vibration direction.